Modern hot water heaters apply intense heat to water in a tank thereby raising the temperature of the water in the tank. Raising the temperature of water causes it to expand which increases the pressure in the plumbing system serviced by the water heater. Such pressure increases cause deformation of the water heater tank and introduce harmful stresses to a plumbing system.
A common solution to the problem of thermal expansion of water in plumbing systems is to install a bladder containing pressure relief tank in communication with the hot water heater. Such pressure relief tanks contain compressible air within their tanks to afford a volume into which thermally expanding water can move and thereby prevent excessive increases of pressure in the plumbing system. Unfortunately, pressure relief tanks require dedicated piping and structural support, are often installed improperly as their air charge pressure must be adjusted to match the supplied water pressure and are subject to failure due to age and the high temperatures which they experience.
To prevent catastrophic damage to a water heater from over-pressuring, water heaters are commonly provided with a water pressure relief valve which is set to vent water when the pressure in a heater reaches a set level, typically 120 p.s.i. When the pressure in the water heater exceeds the relief valve's set point, the relief valve opens and hot water leaks onto the floor adjacent to the water heater creating an undesirable mess.
A presently available device for alleviating this problem is a water pressure relief valve connected within the water storage tank of a toilet wherein the pressure relief valve is preset to exhaust water into the toilet tank when the water pressure in the supplying plumbing system exceeds a set pressure which is lower than the set pressure of the hot water heater's relief valve, such as between 80 to 90 p.s.i. The problem with this system is that the mechanism is relatively expensive as this pressure relief valve must be adapted for a unique coupling or connection situation within the toilet water tank. In addition, this device cannot be easily or securely connected because the water lines in and to the toilet tank are narrow gauge tubing.
It is a principal object of the present invention to provide a water pressure relief apparatus which is inexpensive to manufacture and simple to install in a location which requires no new plumbing lines and no displacement of existing appliances.